Signs Of A Clogged Catalytic Converter

Well you can always stuff one of those cone muffler inserts in the end. Used those on my Triumph TT pipes for awhile but on that, they really did have a negative effect on the power output. Vroom Vrooms indeed.

 

Fairly common when a catalytic converter is starting to get clogged up, actually. I'm not even going to pretend to be an engineer or chemist, but as I understand it, the increasing backpressure, from the flow restriction in the converter can cause the O2 sensors readings to be inaccurate, which then leads to a rich condition, which then leads to more unburned fuel in the catalytic matrix, which leads to clogging..... So on and so forth in a big old vicious circle.

I personally have my hard time wrapping my head around how it leads to a rich condition, you know, what with all those exhaust gasses being jammed into the space between the exhaust manifold and the converter, I'd think it'd cause a lean condition, but it's behavior I've seen more than once.

 

And exactly as you described is how I see it too, but it should result in a lean condition...

Goonna race around the city now, get the computer to relearn the engine and see if I am deaf after all that.. or deafer...

 

Well, I think thats about it. Guess it was a catalytic converter going bad. Even though it wasn't packed solid and some dim light would shine through. The unburnt fuel no longer occurs and the sulphur or "firecracker" smell is gone. Seems to have more power, but with all the noise it makes, who can tell. Feels faster and honestly it feels about as fast as the 225 did when the secondaries were open.

Still does not immediately start when warm, but its not spitting out a bunch of fuel from leaky injectors, so I am going to hold off on the spider replacement for the time being.

So when's this Colorado jeep thing gonna happen this year and who's gonna receive shipment of this jeep?

 

Probably should keep one eye (or ear) open for what might have caused that?

I once removed the cat from my four cylinder YJ, made a bypass pipe. Sounded like a subaru drifter with a fart-can. Bought a new cat...

 

Just being devils advocate here, but are we sure the now-properly-functioning cat isn’t just masking the still-rich condition by thoroughly burning all of the unburnt fuel?

 

No more cat and I cannot smell any unburnt fuel at all..In fact it smells like the perfect mix, unlike any other junk I have owned. I like the idea of a catalytic converter for sure, but I like to drive this thing even more. The spider injectors and or pressure regulator may be bad or possibly just one or 2 injectors are bad. Its about 400 bucks for all the parts to replace it all. I will most likely do it before the possible Colorado trip this year that youre going on...

 

My bad, I thought you replaced the cat, but you just deleted it. I read too fast.

Not sure yet what this summer holds as far as trips go…

 

I could possibly see a clogged cat causing a rich condition on a speed density system. It's basically using intake manifold pressure and temperature to look up how much air is going into the engine in the volumetric efficiency table. Since the actual volumetric efficiency would be down with a clogged cat, less air would be going through the engine than the computer thinks. Since the computer doesn't know this it will still fuel at the original level which is now too much.

A mass-air system where it's directly measuring the amount of air going into the engine wouldn't have this issue.

 

Update!! yay!

Driving the jeep around today, the computer has relearned something and it now runs really rich. I guess I will buy the new spider assembly and install it whenever. At least the Cat wont light on fire because its got a fuel rich condition.

I love the Vroom vrooooom sound of this jeep without the cat.. So loud and dumb.. When you mash the skinny pedal it has zero issues keeping up with traffic.

 

Some kind of performance cat or what? Do they even make such a thing? Seems like an oxymoron.

 

It's not really an oxymoron when you can buy brand new 700+ hp Mustangs and Challengers that have cats on them.

 

Catalytic converters are awesome, but I'm pretty sure this one have a couple hundred K miles on it. Whatever the issue is, I will eventually solve it.. Even if it means the scrapyard! In the mean time, (helmet) loud irritating burnouts blasting Motorhead ,at least in my mind, with unpleasant exhaust is all the rage here. Come get some! race me! You got doors?, cant blow mine off!!

 

I’ll bet Boston Bob or dnb5853 (David) would have space for it.

 

Bought new https://www.rockauto.com/en/moreinfo.php?pk=1002221&cc=1358467&pt=6224&jsn=479&jsn=479&jsn=479 upgraded spider injectors today. Amazon was a lot cheaper, over 50 bucks less than Rockauto and free shipping. Amazon had chinesium brands for less, but I decided on a real name brand even if they come from the same factory.

 

Installed a new spider injector set. The rough idle is gone, no more rich mixture.

the idle is now about 200 rpm higher than I would like and I don’t think it’s adjustable.

 

I honestly can't remember if you can mess with the idle mechanically or not, on those setups, but I don't *think* you can, it needs to be done in the computer.

 

I believe you are correct.... but let me verify.

 

Fixed it with a t-15 drive idle screw in the throttle body